Dynamic motile medium

ABSTRACT

In one embodiment of the invention there is provided a device for modulating light. The device comprises a plurality of nano-scale particles; a conformal structure defining a surface to which the nano-scale particles conform under influence of a displacement force; and a displacement mechanism to apply the displacement force to the nano-scale particles; wherein the nano-scale particles when they conform to the conformal structure change the optical characteristics of the conformal structure.

FIELD

Embodiments of this invention relate to light modulating devices ingeneral, and in particular to light modulating devices that operate onthe principles of diffraction and/or interference, and may be classifiedas transmissive or reflective devices.

BACKGROUND

Electrophoretic devices such as those illustrated in U.S. Pat. No.6,392,785 fall into the class of microencapsulated displacement types,and spinning or re-orientation types. In the former, chargedsubmicroscopic particles contained within fluid filled transparentmicro-shells, can be physically displaced under the influence of anelectrical field. Depending on the color of the fluid and the color ofthe particles, a viewer looking at a sheet containing a dense array ofsuch microshells will see a change in brightness from a dark state to alight state. In the latter, a permanent bipolar charge placed onmicroscopic sphere can be rotated under the influence of an appliedfield. If one side of the particle is black and the other white, theappearance of this device also changes with an applied voltage.

In both cases, the size of the particles, length of the requireddisplacement, and viscosity of the supporting fluidic medium allcontribute to relatively high voltages (approximately 30V-100V) requiredto drive the devices. Additionally, it is costly to incorporate colorinto the resulting media since this generally requires the addition of acostly color films. Speed is also an issue, for the aforementionedreasons.

Another similar approach, based on “liquid powder” offers a similar modeof operation. Analogous to the displacement version of theelectrophoretic approach, this device relies on oppositely chargedparticles of opposite brightness that are physically displaced betweentwo transparent electrodes. A change in brightness is the result. Thischange occurs at high speed because there is no liquid medium, theparticles move through air, with response times of 100 microsecondsachievable. High voltages of 80V-150V, due to the required largedimensions between electrodes, and costly color also constrain thecapabilities of this device.

U.S. Pat. No. 6,215,920 describes an optical modulator whose primaryoptical principle is that of total internal reflection. A corner-cubereflector directs incident light back to the source by exploiting thetotal internal reflection (TIR) at the walls of the corner-cube.Particles which are brought into contact with the walls can spoil ordegrade the TIR, thus reducing reflectivity significantly and theoverall reflection of the structure. This approach, while offering theprospect of very high inherent reflectivities, does not incorporate ameans for color selection. The design is further complicated by thetradeoff between positioning of the drive electrodes which could eitherdegrade reflectivity (if located on the walls) or increase voltage (iflocated on the incident plane of the corner cube).

SUMMARY

According to one aspect of the invention, there is provided a device formodulating light, comprising: a fixed geometry component to modulatelight, said component providing at least one conformal surface; and aplurality of motiles that are displaceable to conform to the conformalsurface, an optical response of the fixed geometry component to incidentlight when the motiles conform to the conformal surface being differentfrom when the motiles do not conform to the conformal surface.

According to another aspect of the invention there is provided a devicefor modulating light, comprising: a light modulating component in theform of a walled structure defining a cavity, said walled structurehaving an upper and a lower wall, a spacing between the upper and lowerwalls being fixed; a plurality of movable particles located within thelight modulating component; and a displacement mechanism to cause themovable particles to move from a non-activated condition to an activatedcondition in which the movable particles conform to at least one of theupper and lower walls, an optical response of the light modulatingcomponent to incident light when in the movable particles are in theactivated condition being different from when the movable particles arein the non-activated condition.

According to yet another embodiment of the invention there is provided adevice modulating light, comprising: a plurality of nano-scaleparticles; a conformal structure defining a surface to which thenano-scale particles conform under influence of a displacement force;and a displacement mechanism to apply the displacement force to thenano-scale particles; wherein the nano-scale particles when they conformto the conformal structure change the optical characteristics of theconformal structure.

Other aspects of the invention will be apparent from the detaileddescription below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings shows an example of prior art illustrating adisplacement type electrophoretic modulator.

FIG. 2 of the drawings shows an example of prior art illustrating a TIRbased modulator with movable particles.

FIG. 3 of the drawings is an example of prior art illustrating adiffraction based modulator

FIG. 4 of the drawings illustrates a motile based cavity which exploitsdiffraction, in accordance with one embodiment of the invention.

FIG. 5 of the drawings illustrates a multifunction motile based cavitywhich exploits reflectivity, in accordance with one embodiment of theinvention.

FIG. 6 of the drawings illustrates a motile based photonic crystalmodulator, in accordance with one embodiment of the invention.

FIG. 7 of the drawings illustrates the optical behavior of aninterference based cavity.

FIG. 8 of the drawings illustrates a motile based cavity which exploitsinterference, in accordance with one embodiment of the invention.

FIG. 9 of the drawings illustrates a multicolor motile based cavitywhich exploits interference, in accordance with one embodiment of theinvention; and

FIG. 10 of the drawings illustrates one embodiment of a manufacturingsequence, in accordance with one embodiment of the invention.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the invention. It will be apparent, however, to oneskilled in the art that the invention can be practiced without thesespecific details. In other instances, structures and devices are shownin block diagram form only in order to avoid obscuring the invention.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not other embodiments.

Referring to FIG. 1 of the drawings, one variation on an electrophoreticmodulator is illustrated. Voltage source 10, applies an electric fieldto electrodes 11 and 12. This field acts on charged particles groups 14and 15, which are charged positively and negatively respectively, andcontained in a transparent microshell 13, which is suspended within afluid contained by the microshell 13. Depending on the opticaltransmissivity of the fluid, and the color of the particles, the viewer16, will see different colors depending on the applied voltage. Forexample, if the fluid is transparent, and the negatively chargedparticles are colored black, while the positively charged particles arecolored white, the microshell will appear black in the state asillustrated.

Referring to FIG. 2, a corner cube reflector is shown with light 25,reflecting from the walls 29, and particles 21 suspended away from thewalls. With particles 21, brought into contact with walls 23 via theapplication of a voltage 24, TIR is defeated, and light 26, is notreflected.

Referring to FIG. 3, a structure known as a grating light valve isillustrated. Light valve 300, is shown in the undriven state whereingrating fingers 306 are suspended above reflecting substrate 302. Thegrating fingers 306 are reflective. Spacing 308 between the grating 306and the reflecting substrate 302 is such that the grating behaves as aflat mirror to incident light 310, producing reflected light 312 withminimal losses. Application of a voltage between the reflectingsubstrate 302, and alternating grating fingers 306, causes half of thefingers to be drawn into contact with the reflecting substrate 302.Light valve 320, illustrates the resulting configuration, which acts asa reflecting diffraction grating, scattering reflected 316, at varyingangles depending on the color.

Referring to FIG. 4, a diffraction mode motile modulator is illustrated.Analogous to the light valve of FIG. 3, similar optical behavior can beachieved with the application of a voltage, but without the complexityof patterning and controlling the properties of grating fingers.Transparent conductors 402 have dimensions similar to the gratingfingers 306, but are transparent. Thus the transparent conductors 402have no effect on incident light when voltage 406 is applied. Whenvoltage 404 is applied between transparent electrodes 402 and reflectingelectrode 410, the motiles 404 migrate, align and adhere to theelectrodes 402 to form a grating which acts on the incident light 408,in a diffractive fashion according to the dimensions of the grating.

Referring to FIG. 5, a more generalized motile based modulator is shown.According to embodiments of the invention, any two-dimensional orthree-dimensional template, cavity, or periodic structure can havedynamic optical behavior if the material and optical properties of itssurfaces can be altered by the displacement of a movable material, or afield of motiles. In one embodiment of the invention, any opticallyneutral structure that has a physical form or can be precisely defined,for example using a microscopic or submicroscopic mold, acts as a fixedgeometry component or template which provides a conformal surface formotile particles. So that application of a voltage creates a motileshell which takes the form of the template. The motile shell is atemporary structure that acts on light in accordance with the geometryof the template, and the optical and material properties of the motilemedium. Possible devices include reconfigurable photonic crystals,reconfigurable reflective, refractive, diffractive, optics, andreconfigurable sub-wavelength structures. The modulator in FIG. 5includes a parabolic component 508, and a wedge-shaped component 510.With voltage 506 applied, incident light passes through these componentswithout effect. A suitable displacement mechanism causes the motilefield to migrate and conform to the surface of these optical componentsthus changing their optical properties. The displacement mechanism maytake the form of an electrostatic, magnetic, thermal, or acousticdisplacement mechanism. In the case of an electrostatic displacementmechanism a voltage 504 may be applied to cause migration of themotiles. Migration of the motiles causes the component 508 to become aparabolic reflector, and the component 510 to become a wedge reflector,with each acting on the incident light in the appropriate fashion.

Referring to FIG. 6, yet another motile-based modulator is shown toinclude forms and structures 600 which may be formed by a massreplication technique such as embossing, micro-embossing, stamping,electroforming, thermoforming, printing, and injection molding. Theforms and structures 600 may themselves be sub-micron in size. Withproper design, the forms and structures 600 are capable of acting onlight in an interferometric and/or diffractive way, not unlike that of aphotonic crystal. The modification of the properties of the forms andstructures 600 by the electrostatic displacement of appropriate motilesunder an applied voltage 610 can alter the optical behavior of the formsand structures 600 in advantageous ways, thus allowing for theredirection and/or modification of light 602, which is incident on thestructure. Arbitrary structures similar to the structures 600 may beformed to alter one or more of frequency, phase, amplitude, and exitangle of incident light and reconfigured if the material and dimensionalproperties are properly defined, in accordance with the techniquesdisclosed above, The film or form may be of any shape or form, as longas the dimensions between it and the counter-film can be defined andmaintained. This includes flat, curved, cylindrical or fiber like, andspherical. Many other configurations are possible and limited only bythe ability to define the molds and generate and incorporate theappropriate motile materials.

Based on the foregoing, embodiments of the invention include displacingthe motiles from a quiescent or non-activated condition to an activatedcondition in which the motiles conform to a conformal surface providedby one of the above-described structures that acts as a template. Thedisplacement is by a displacement mechanism that can include anelectrostatic displacement mechanism. In one embodiment, the motiles maybe randomly orientated when in the non-activated condition. In oneembodiment, the optical characteristics of a modulator that uses themotiles changes as soon as the motiles begin to move under influence ofthe displacement mechanism.

Referring to FIG. 7, three modes of operation are illustrated for aninterferometric cavity. Cavity 700 is shown schematically as a stack ofcomponents comprising a transparent substrate 702, an absorbingsemitransparent film (such as a lossy metal) 704, an insulator/spacer(such as a metallic oxide) 706, airgap 708, and a movable mirror (also ametal) 710. Light 714, which is incident on the cavity produces astanding wave 712, whose peak, resides within the airgap 708 and isconsequently not attenuated. A particular frequency of light isreflected, with the frequency determined by the size of the air gap. Thefilm 704, contains materials such as metals, which are highly absorbing.When the movable mirror 710 is brought into contact with theinsulator/spacer, as shown in modulator 720, the peak of standing wave722 is displaced. Proper design of the insulator/spacer causes the peakto reside in the induced absorber 726, resulting in attenuation, and theelimination of reflected light.

In cavity 730, insulator/spacer 718, is enlarged, such that when themovable mirror 742, is brought into contact, as shown in cavity 740, thestanding wave peak does not reside in the lossy metal. Thus, instead ofswitching from a reflecting mode to an absorbing mode, the cavityswitches between reflecting one color, and reflecting another color.

Cavity 760 is shown without an insulator/spacer. In the undriven state,the dimensions of the cavity are chosen such that the standing wave peak762, resides within the lossy metal 764. Thus no light is reflected.When the movable mirror 772, is brought into contact with the inducedabsorber 774, as shown in cavity 770, the cavity acts as a mirror. Thusmuch light is reflected with minimal losses.

A motile modulator is illustrated in FIG. 8. A cavity structureanalogous to that shown in FIG. 7 is shown. In modulator pair 800,voltages 802 and 804 are applied between electrodes 814/818, and lossymetal 810. These components are patterned and deposited on films 806 and808. The spacing between the films is such that light which is incidenton the cavity is acted on via interference. The cavity may contain afluid of organic or inorganic composition, a gel of similar composition,or may be comprised of a gas or vacuum. Motiles 814 and 816, arecollections of nano-scale structures which can range fromthree-dimensional particles to flat two-dimensional and plate like intheir geometry. For interferometric applications involving light in thevisible range, and particle like motiles, their size should be less than100 nm, with smaller sizes reducing scattering effects. Fortwo-dimensional motiles, the thickness is less important, but thesurface roughness must be less than 100 nm. The motiles may beconducting, semiconducting, or insulating. The motiles may also carry afixed charge, or be capable of acquiring a charge. Because the motilesare mechanically decoupled from any of the surrounding structures andwalls, they are free to move under the influence of an applied electricfield, though other mechanisms including magnetic, thermal, or acousticmeans of actuation are possible. Consequently, the optical properties ofthe cavity can be manipulated by the positioning of the motiles.

In the case of FIG. 8, the motiles are metallic, preferably a metal withhigh reflectivity such as aluminum or sliver. With voltage 802 applied,an optical effect like that shown in cavity 700 of FIG. 7 can beachieved if the cavity dimensions are comparable. Similarly with voltage804 applied, the optical effect illustrated in cavity 720 of FIG. 7 canbe emulated. Motile modulators 820 and 840, are configured to emulatethe behavior of cavities 730/740 and 760/770 respectively. Modulator 820incorporates thicker spacer 822, such that the associated standing wavealways remains unattenuated. Modulator 840 contains no spacer, and thecavity dimensions are such that with voltage 842 applied a dark state isachieved, and with voltage 844 applied, a white state is achieved. Thecavity structures are identical, but instead of a movable mirror amotile field is displaced.

Behavior of the motiles in such cavities will be influenced by theircomposition. For metallic motiles, an attractive force is experienceduntil they move into contact with the opposite electrode whereupon theyare charged to the polarity of that electrode and are no longer pulled.A similar phenomenon occurs with insulating motiles, though the processof charging to the opposite polarity takes longer as they areinsulating. Consequently, selection of particles of different degrees ofconductivity provides a means for manipulating the electrodynamicbehavior of the motiles and therefore the dynamic optical behavior ofthe modulator. Similarly for motiles which have inherent charge, thelevel of charge will have an effect on the behavior of the structure.Under certain circumstances, with the application of a certain voltageor voltage sequence in conjunction with motiles of the appropriatematerial, it is possible to dynamically manipulate the charge within themotiles. This adds another means for manipulating behavior. Thecombination of one or more of these techniques can enable themanifestation of an electro-fluidic hysteresis. Allowing theestablishment of a voltage switching threshold and facilitatingaddressing using line-at-a-time techniques which are known generally forthose who design and utilize devices which are configured as addressablearrays.

Referring to FIG. 9, a three color motile modulator pixel is shown withthree different cavity gaps, 902, 904, and 906. Pixels with as few asone cavity or more than three are also possible depending on the colorrequirements of the application. The film material, 900, could be of anynumber of materials that are easily formed using embossing, stamping, ormicro-replication. These include plastics such as polycarbonates, PMMA,polyimides, or thermoplastics. Metal foils may also be utilized thoughthey might require a special surface treatment for feature insulation.For stamping or embossing, a suitable mold is defined using a precisionmachining tool to define the depth of the cavities and lateraldimensions of the electrode wells or channels. Then one of the manystamping or embossing processes, which are well known in the art, isutilized. Special emphasis is placed on compensating for any shrinkageduring curing so that the proper vertical cavity dimension is achieved.

Common electrode 908, may not be required if the film 900 is conductingas in the case of the foil. Counter film 910, is flat, and supports theother components, such as addressing electrode 912, which for aninterference mode device could include a lossy metal and possibly andinsulator spacer (or other appropriate structures for diffractive,reflective or photonic crystal behavior). Counter film 910 should be ofa transparent material such as the aforementioned plastics or glass.Alternatively, film 906 could be transparent while counter film is not,or both films may be transparent. In all cases at least one film must betransparent, and by necessity this is the film which must support theoptically active thin films (i.e. lossy metal and/or insulator).

The exposed surface of counter film 910 may also have a pattern etchedor stamped into it to enhance optical properties. These could bediffuser, lens, or grating like structures. Properties such as viewingangle, contrast, and irridesence could be modified with the propertreatment. The inner surface of counter film 910 may also incorporatetopography in the manner of the structures 508 and 510 in FIG. 5.Further modifications to optical performance may be achieved when themotiles are driven and conform to the features of counter film 910.

From a manufacturing standpoint, modulating media based on dynamicmotiles are advantageous because they 912 thieve the manufacturingsimplicity and cost structure of electrophoretic style media. Thisderives in part from the fact that they combine readily availablemotiles in the form of volume manufactured nano-powders, with fixedcavity structures whose dimensions can be defined using cost effectivestamping, embossing, or micro-replicating techniques among others.

Nano-powders are available from a wide and growing variety ofmanufacturers that include Inframet Advanced Materials of Farmington,Conn., and Sigma-Aldrich of St. Louis, Mo. One standard product of thelatter is a silver nano-powder with particles on the order of 70 nm indiameter.

Referring to FIG. 10, one embodiment of a manufacturing sequence isillustrated. In step one, a nano-powder of a particular material isselected on the basis of the desired optical, physical, and dimensionalproperties. In step two the nano-powder is mixed with a liquid polymersolute which may or may not be photodefinable. In one embodiment, thesolute component may be organic. The ratio of the mixture is determinedby the amount of nano-powder desired per unit volume in the resultingdevice. In step three, the resulting mixture is applied to an embossedfilm, for example by printing. Thereafter a curing process is used todrive off the bulk of the solvent. Step four relies on any one of wellknown low temperature techniques for converting organic materials intogaseous byproducts. Such low temperature techniques include oxygenplasma etching, and UV ozone cleaning among others. These techniquesallow the resulting motile aggregates to reside in the locations inwhich they were “printed” without relocation which would result if a wetdissolution process were utilized. Step five demonstrates theencapsulation of the film with a counter film which has been treated orotherwise processed for the desired application.

Ink-jet or other printing techniques may also be utilized to effectivelydeposit and pattern the motile aggregates. These could be suspended in asolvent and printed like an ink at the required location on the film.Alternative but related techniques also involve the placement of motileaggregates by printing, ink-jet or other means. In one embodiment, amixture of a photo sensitive prepolymer and the nano-powder may beprinted at the selected locations. Proper composition of this mixtureand subsequent exposure to a UV source can result in photo enforcedstratification. The result is the motile aggregate is suspended within apolymeric capsule. This technique is described for application to LCmaterials in a paper entitled, “Inkjet Printed LCDs” J. P. A. Vogels, etal, Proceedings of the 11^(th) International Display Workshops,Niigatta, Japan, 2004.

Electrodes, mirrors, and spacers, may be easily deposited and patternedusing conventional deposition techniques, such a sputtering or plating,and patterning techniques such as micro-lithography and printing. At thesame time, some of the challenges of fabricating MEMS structures areavoided. These include stress control in movable components, dimensionalcontrol using highly uniform deposited sacrificial materials, and theprocess issues associated with combining these and other steps.Performance requirements for insulating materials including integrity,continuity, breakdown voltage and leakage currents, are also relaxed,compared to the MEMS devices. This is because the motiles are notcontinuously electrically coupled. Therefore issues of shorting arebetween a movable and permanently coupled component and the cavitystructures (as in the conventional MEMS approach) are avoided.

Such modulators can be fabricated in large arrays on flexible sheets ofplastic or other materials. This sheet may then be applied or adhered tovirtually any surface whereby it may be used to electronically alter theappearance of that surface, or portray information in the form ofdynamic two-dimensional media. The film is also flexible, againdepending on the material, and therefore suitable for applications wherethe film or “dynamic reflective motile medium” can be applied to curvedor arbitrary surfaces, which may or may not be flexed during the courseof their use.

Applications include all kinds of visually perceived media ranging fromlabels on cans, bottles, and other consumable goods. Packaging forproducts, goods, parts, and parcels thereof that convey any kind ofgraphical, textual, or visually conveyed impression, concept, picture,or information. Clothing or goods made from fabrics or other flexiblematerials. Any product which has as one function to serve a decorative,informational, or hybrid function such as product exteriors andhousings, walls, furniture, jewelry, surfboards snowboards. Electronicproduct exteriors or portions thereof that are viewed by the user and/orothers. Vehicles, such as motorcycles, trucks, and automobiles. Theinterior/exterior walls of buildings and other permanent orsemipermanent structures. Photonic materials designed to manipulatelight and other forms of electromagnetic radiation are possible.Frequency sensitive mirrors whose behavior in the reflection vs.frequency space may be reconfigured, coatings for energy efficient glassused in skyscrapers, or contrast and brightness controlled sunglassesare possible.

Dynamic media from small to large format ranging from timepieces, booksand magazines, TV sized to kiosk, billboard, and beyond. Any part, orproduct, or consumer good of any sort whose external appearance isconsidered an important characteristic can have its surface treated orcoated with a motile media film, and have its appearance modified in acontrolled fashion. Although the present invention has been describedwith reference to specific exemplary embodiments, it will be evidentthat the various modifications and changes can be made to theseembodiments without departing from the broader spirit of the inventionas set forth in the claims. Accordingly, the specification and drawingsare to be regarded in an illustrative sense rather than in a restrictivesense.

1. A device for modulating light, comprising: a fixed geometry componentto modulate light, said component providing at least one conformalsurface; and a plurality of motiles that are displaceable to conform tothe conformal surface, an optical response of the fixed geometrycomponent to incident light when the motiles conform to the conformalsurface being different from when the motiles do not conform to theconformal surface.
 2. The device of claim 1, wherein the conformalsurface is planar.
 3. The device of claim 2, wherein conformal surfaceis provided by discreet planar elements that are linearly spaced apart.4. The device of claim 3, wherein the device acts as a diffractiongrating when the motiles conform to the conformal surface provided bythe discreet planar elements.
 5. The device of claim 1, wherein theconformal surface is three-dimensional.
 6. The device of claim 5,wherein the conformal surface is provided by discreet rod-like elements.7. The device of claim 6, wherein the conformal surfaces provided by thediscreet rod-like elements in combination with the motiles producediffraction and interference effects on incident light.
 8. The device ofclaim 1, wherein the fixed geometry component comprises a walledstructure that defines a cavity, wherein one of the walls of thestructure forms the conformal surface.
 9. The device of claim 8,comprising three of said walled structures disposed in a linearconfiguration, each of a different size and producing a differentoptical response to incident light when said motiles conform to theconformal surface thereof.
 10. The device of claim 1, wherein the fixedgeometry component is produced using a mass replication technique. 11.The device of claim 10, wherein the mass replication technique isselected from the group consisting of embossing, micro-embossing,stamping, electroforming, thermoforming, printing, and injectionmolding.
 13. The device of claim 1, further comprising a displacementmechanism to displace the motiles towards the conformal surface.
 14. Thedevice of claim 13, wherein the displacement mechanism applies anelectrostatic force to displace the motiles.
 15. The device of claim 13,wherein displacement mechanism is selected from the group consisting ofa magnetic, a thermal, and an acoustic displacement mechanism.
 16. Adevice for modulating light, comprising: a light modulating component inthe form of a walled structure defining a cavity, said walled structurehaving an upper and a lower wall, a spacing between the upper and lowerwalls being fixed; a plurality of movable particles located within thelight modulating component; and a displacement mechanism to cause themovable particles to move from a non-activated condition to an activatedcondition in which the movable particles conform to at least one of theupper and lower walls, an optical response of the light modulatingcomponent to incident light changing responsive to the movement of themovable particles under influence of the displacement mechanism.
 17. Thedevice of claim 16, comprising three of said light modulating componentsdisposed in a linear configuration, wherein each light modulatingcomponent has a different spacing between the upper and lower walls. 18.The device of claim 16, wherein the light modulating particles includenano-scale particles.
 19. The device of claim 16, wherein thedisplacement mechanism applies an electrostatic force to the movableparticles to cause displacement thereof.
 20. A device modulating light,comprising: a plurality of nano-scale particles; a conformal structuredefining a surface to which the nano-scale particles conform underinfluence of a displacement force; and a displacement mechanism to applythe displacement force to the nano-scale particles; wherein thenano-scale particles when they conform to the conformal structure changethe optical characteristics of the conformal structure.
 21. The deviceof claim 20, wherein the conformal structure is fabricated through areplication technique.
 22. The device of claim 21, wherein the massreplication technique is selected from the group consisting ofembossing, micro-embossing, stamping, electroforming, thermoforming,printing, and injection molding.